I'm having problems with people leaving comments to articles on my site, scottjosephorlando.com.

Some people are completely unable to leave a comment and get only an error message. Myself, when I respond to someone's comment, I get an error message, the testarea turns to coding but the comment posts anyway. (This last one has happened before; my original site designers did something to fix it but the problem has returned -- possible after I upgraded to the latest version of Joomla?)
I'm using joomlacomment v. 3.26, so I know at the very least I should install the upgrade -- might this fix it?
Thanks
Scott